It is well known from the Japanese Publication No. Sho 42-12318 that a bonding and filling material which uses alkyl boron as a hardening agent in acryl resin, has a strong bonding strength to bone or teeth and is useful for dental and surgical use. Alkyl boron which is used as the hardening agent, however, is a highly unstable substance which is liable to ignite by easily reacting with oxygen in the air and liable to lose its activity as the hardening agent by hygroscopicity. To remove this drawback, various methods have been proposed, but with no satisfactory results.
As stated above, alkyl boron is so unstable to oxygen in the air that it is usually stored in a sealed ampule. This method of storage, however, though it is perfect, has the drawback that the ampule must be sealed again after every use; and every time it is unsealed, the air is admitted and thereby the activity of the hardening agent contained therein drops, with the result that it is not possible to obtain a polymer of constant physical properties each time. Meanwhile, since alkyl boron is a colorless liquid of low viscosity, there is a hazard of the liquid flowing out and getting ignited when the vessel with an imperfect seal happens to fall.
A bonding and filling material which uses alkyl boron as a hardening agent, is thus so excellent in performance that removal of the above drawback by some method has been strongly demanded from dentists and surgeons.